Bimetallic thermostats are known comprising an external covering which supports an internal device made up of a base provided with packing which supports contact feet which allow the connection with external devices, an exchange relay connected with the base by means of electric wires and a sensitive thermostatic element connected in turn with said relay by means of contact feet.
The space present between the external covering and the internal device is generally occupied by insulating resin in order to prevent the feet of the thermostat from touching the projecting wires of the relay.
What follows is that the manufacture of a thermostat as described above is rather complex and expensive In addition in the case of breakdown the repair turns out to be difficult if not impossible; the entire thermostat must often be replaced.